Abstract
.Typhoid fever remains an important public health problem in low- and middle-income countries, with large outbreaks reported from Africa and Asia. Although the WHO recommends typhoid vaccination for control of confirmed outbreaks, there are limited data on the epidemiologic characteristics of outbreaks to inform vaccine use in outbreak settings. We conducted a literature review for typhoid outbreaks published since 1990. We found 47 publications describing 45,215 cases in outbreaks occurring in 25 countries from 1989 through 2018. Outbreak characteristics varied considerably by WHO region, with median outbreak size ranging from 12 to 1,101 cases, median duration from 23 to 140 days, and median case fatality ratio from 0% to 1%. The largest number of outbreaks occurred in WHO Southeast Asia, 13 (28%), and African regions, 12 (26%). Among 43 outbreaks reporting a mode of disease transmission, 24 (56%) were waterborne, 17 (40%) were foodborne, and two (5%) were by direct contact transmission. Among the 34 outbreaks with antimicrobial resistance data, 11 (32%) reported Typhi non-susceptible to ciprofloxacin, 16 (47%) reported multidrug-resistant (MDR) strains, and one reported extensively drug-resistant strains. Our review showed a longer median duration of outbreaks caused by MDR strains (148 days versus 34 days for susceptible strains), although this difference was not statistically significant. Control strategies focused on water, sanitation, and food safety, with vaccine use described in only six (13%) outbreaks. As typhoid conjugate vaccines become more widely used, their potential role and impact in outbreak control warrant further evaluation.
Highlights
Typhoid fever is a systemic febrile illness caused by Salmonella enterica serovar Typhi (Typhi) responsible for an estimated 11–21 million illnesses and 65,000–188,000 deaths worldwide each year.[1,2,3,4,5,6] In areas of Asia and sub-Saharan Africa, with high typhoid incidence (> 100 cases/100,000 persons per year), large outbreaks with Typhi strains resistant to multiple antimicrobials[7,8,9,10,11] have been reported from both rural and urban settings where access to safe food, water, and sanitation is limited
We reviewed the literature for typhoid fever outbreaks published since January 1, 1990 to describe the global epidemiology of typhoid outbreaks and outbreak responses
The studies included in this review were identified by independently searching three electronic databases (PubMed, Google Scholar, and Ovid), screening the reference list of an International Vaccine Institute (IVI) manuscript,[31] and merging preexisting literature searches obtained by the U.S CDC and the WHO
Summary
Typhoid fever is a systemic febrile illness caused by Salmonella enterica serovar Typhi (Typhi) responsible for an estimated 11–21 million illnesses and 65,000–188,000 deaths worldwide each year.[1,2,3,4,5,6] In areas of Asia and sub-Saharan Africa, with high typhoid incidence (> 100 cases/100,000 persons per year), large outbreaks with Typhi strains resistant to multiple antimicrobials[7,8,9,10,11] have been reported from both rural and urban settings where access to safe food, water, and sanitation is limited. Increasing resistance has limited antimicrobial treatment options: multidrugresistant (MDR) strains, defined as resistant to the three former first-line antimicrobial agents (ampicillin, chloramphenicol, and trimethoprim–sulfamethoxazole), have been widespread in Asia since the early 1990s and have been increasing in many regions of Africa.[12] treatment with ciprofloxacin increased since the late 1990s, with the associated widespread fluoroquinolone resistance emerging among Typhi isolates from Asia and parts of Africa. In 2016, the first outbreak of an extensively drug-resistant (XDR) Typhi strain, with resistance to ceftriaxone, ciprofloxacin, and traditional first-line agents, was reported in Pakistan.[13,14,15]. Immunogenicity, efficacy, and effectiveness of Vi polysaccharide (ViPS) and Ty21a typhoid vaccines have
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